The present invention relates to a positive-displacement fluid machine which makes a space communicating with an intake opening closed by a pair of members engaging with each other and move to an outlet opening in order to receive fluid from the intake opening and discharge it from the outlet opening.
JP 2004-286025 A1 by the present applicant discloses a scroll type fluid machine which comprises at least a casing, a follower scroll unit constituted of at least an outer peripheral block rotatably held to the casing and a follower wrap extending helically inwardly from the outer peripheral block, a driving scroll unit comprising a driving wrap engaging with the follower wrap, a pair of end plates grasping and fixing the driving wrap and holding the follower wrap slidably and a driving shaft eccentric to the follower scroll unit and supported rotatably to the casing to rotate the end plates in order to define compression spaces together with the follower scroll unit, an intake opening communicating with the first compression space and an outlet opening formed in the driving shaft and communicating with the last compression space.
JP 4-11297 U discloses a blower comprising a centrifugal impeller having a plurality of blades provided radially between an upper shroud plate and a lower shroud plate, fixed guide vanes provided around the centrifugal impeller and a fan cover covering them, wherein short fibers are bonded circularly on a surface opposite to the upper shroud plate of the fan cover by electrostatic flocking.
For instance, in a prior scroll type fluid machine disclosed in JP 2004-286025 A, in compression spaces defined by a pair of scroll wraps and a pair of end plates grasping the scroll wraps, it is well known that it is necessary to prevent leakage from parts on which side surfaces of the scroll wraps close the compression spaces in minute gaps (RC gaps) and minute gaps (AC gaps) between top surfaces of the scroll wraps and the end plates and that this leakage greatly influences performance of the scroll fluid machine. Generally, it is said that it are preferred that RC gaps is not more than 50 μm.
Accordingly, it was necessary to increase processing accuracy and assembly accuracy of all combination parts so as to make minute gap parts (RC gaps) between side surfaces of the scroll wraps and minute gap parts (AC gaps) between the top surfaces of the scroll wraps and the end plates respectively as small as possible in the prior art. Besides, it was necessary to constitute a tip sealing and the like in order to prevent leakage in the AC gap parts. Furthermore, because damage of the wraps occurs by breaking down and seizing by contact between the scroll wraps when the aforementioned gaps are made smaller, the scroll wraps must be processed using expensive surface treatment such as hard anodized aluminum treatment and the like in order to prevent breaking down and seizing. Thus, there is a disadvantage that the scroll fluid machine itself becomes expensive by increasing accuracy of finishing in order to make the aforementioned gaps smaller, by adding sealing parts and by performing expensive surface treatment.
Besides, as disclosed in JP 4-11297 U, it is very effective to seal gaps with short fibers by electrostatic flocking.